Touch-sensitive displays (e.g., touch screens) allow users to input commands and data directly into a display, which may be particularly useful in a variety of applications. Common applications for touch screens include consumer products such as cellular telephones and user interfaces for industrial process control. Depending on the specific application, these touch-sensitive displays are commonly used in devices ranging from small handheld PDAs, to medium sized tablet computers, to large industrial implements. It is often convenient for a user to input and read data on the same display. Unlike a dedicated input device, such as a keypad with discrete well-defined keys, most touch-sensitive displays are generally flat. As a result, touch-sensitive screens do not provide significant tactile guidance for one or more control “buttons”. Instead, touch-sensitive displays rely on visual cues (e.g., displayed images) to guide user input.
Hence a serious drawback of touch-sensitive displays is the inherent difficulty a user faces when attempting to input data accurately because adjacent buttons are not distinguishable by feel. Improper keystrokes are common, which typically forces the user to focus both on the keypad (to properly input the next keystroke) and on the text input line (to check for errors); generally, the user is forced to keep his or her eyes on the display. The importance of tactile guidance is readily apparent in the competition between the Apple's iPhone and RIM's BlackBerry 8800. Touch-sensitive displays and physical hard buttons each have benefits and drawbacks, and digital devices generally incorporate one such component or the other.
Thus, there is a need in the touch-based interface field to create a new and useful interface, for a digital display, that incorporates tactile guidance for one or more control buttons.